Negative power indicates that it is a ___.
concave lens
convex lens
combination two convex lenses
Power=1Focal length ⇒ Since concave lens have negative focal length, power of concave lens is also negative.
A convex lens of power 5 D and a concave lens of power 7.5 D are placed in contact with each other. What is the :(a) power of this combination of lenses?(b) focal length of this combination of lenses?
a convex lens of power 5D is combined with a concave lens of power 4D,the focal lenght of the combination is?